Treatment of circuit support with impulse excitation

ABSTRACT

The devices and methods of the art do not readily allow moistening of, removing gas bubbles from and/or increasing the transfer of material in through bores and/or pocket holes in printed circuit boards (PCB). Considerable problems are presented by the treatment of very narrow bores with high aspect ratios in particular. To overcome this problem a method was found that involves the following stages: the printed circuit boards PCB are passed through a processing plant on a horizontal conveying path and in one conveying plane  2  by means of transportation means  13, 14  and are thereby brought to contact a liquid for treatment, wherein mechanical pulses are directly transmitted to the printed circuit boards PCB via the transportation means  13, 14  and/or via the liquid for treatment by means of pulse generating means  50.

The invention relates to a method and a device for treating circuitcarriers provided with through holes and/or cavities. The method and thedevice may be used in particular for promoting moistening of, forremoving gas bubbles from and/or for increasing the transfer of materialin through bores and/or pocket holes in printed circuit boards.

For manufacturing printed circuit boards, printed circuit films andother circuit carriers such as chip carriers and multichip modules,employment is made of electroplating processes in order to create thecircuit section on the outer sides of these boards, films or carriersand to provide the walls of the bores with a conductive coating for theelectrical connection of several circuit planes. The principal methodsused in this connection are pretreatment, aftertreatment as well asmetallization. Pretreatment includes cleaning, etching and activatingprocesses and after treatment includes etching, passivation and othermethods for supplying protective coatings. The methods more specificallyused in metallization are electrolytic methods, reductive (electroless)chemical methods and cementation.

As the packing density in the circuit carriers increases, the bores arerequired to have an ever smaller diameter. The liquid for treatment isno longer capable of penetrating readily such narrow bores. The finalremoval of liquid in the drying process is no longer readily possibleeither. The transfer of material between the treating bath and theinterior of the bores becomes very poor particularly when the diameterof the bores is small while the carriers are very thick. The ratio ofthe carrier thickness to the diameter of the bore (aspect ratio)determines the transfer of material. If the bores that traverse thecarrier have an aspect ratio of 6:1 and more, problems may occur inelectrolytic treatment when no additional provisions are made forreinforcing the transfer of material. So-called pocket holes inparticular, which only project into the carrier material from one side,are difficult to be treated with the liquids for treatment. With thesebores, which are in parts very small (diameter of 100 μm for example),an aspect ratio of 1:1 may already cause considerable problems.

To eliminate these difficulties, numerous suggestions have already beenmade. It has been proposed for example to have the circuit boards thatare dipped into a solution for treatment moved slowly back and forth atright angles with the surface of the board in order to achieve a throughflow at least in the through holes. Air is in parts additionally enteredinto the treating baths in order to thus generate a strong convection inthe baths. These measures however very soon proved insufficient to havethe very small bores, which have a diameter of 0.5 mm and less,efficiently circulated.

To mitigate the problems, there has been described in DE 30 11 061 A1 amethod for intensifying swilling and cleaning processes for bores inprinted circuit boards. To this effect the printed circuit boards areconveyed on a horizontal conveying path and in a horizontal operationalposition through a processing plant and are guided in the processthrough a line where they are splashed at with a flushing agent, saidliquid flushing agent being delivered from said line to the underside ofthe printed circuit boards via open seam tubes. In so doing, theflushing agent also reaches the downward opening bores. Lacquers andliquid etching agents may thus efficiently be scoured from the holes andother openings.

A similar arrangement for cleaning, activating and/or metallizingboreholes in horizontally guided printed circuit boards has beenindicated in EP 0 212 253. In this case too, the printed circuit boardswhich are guided in horizontal operational position are led past afacility that is provided with a nozzle arranged underneath theconveying band at right angles with the direction of transportation. Thenozzle used is a splash nozzle that delivers the liquid treating agentnormal to the sides of the boards.

According to EP 0 329 807 B1, further improvement is effected byproviding, in addition to a splash nozzle, a suction equipment on thatside of the board that is averse to the splash nozzle, said suctionequipment being arranged on a surface of the board which is guided inhorizontal direction and in a horizontal operational position. It isalso considered to be of advantage that scoured impurities are said tobe prevented from depositing on the surfaces of the boards.

DE 40 40 119 C2 describes a method of leading a flow through bores inprinted circuit boards which are conveyed in a horizontal operationalposition and on a horizontal conveying path. Rollers arranged oppositeeach other and abutting on either side of the printed circuit boards areprovided for delivering liquid for treatment. In operation, the liquidfor treatment is conducted via the hollow space to the one roller(nozzle cylinder), passes through the discharge openings thereof, whichare open in contact between the nozzle cylinder and the board, isdirected through the bores in the boards and enters the counter pressureroller, which is hollow as well, through intake openings. Valves whichare solidly connected to a fluid permeable casing are provided in thedischarge openings of the nozzle cylinder. If the valves are lifted outof the valve seat, the liquid is channelled through the cleared annularpassage and is advanced to the bores.

EP 0 752 807 A1 describes another device for treating printed circuitboards. The printed circuit boards are conveyed in a horizontaloperational position and in a horizontal conveying direction pastfacilities consisting each of a slotted tube and of a feed cylinderarranged within said tube. The slot of the tube is open to the conveyingplane. Part of the feed cylinder protrudes from the slot to carry theboards along. Narrow gaps are formed between the boundaries of the slotand the cylinder through which liquid for treatment, which has beenforced under pressure through the tube, may be discharged and advancedto the boards and through the bores in the boards.

Another possibility to intensify the transfer of material in the boresconsists in achieving improved circulation of fluid in the bores bymeans of vibration equipments.

To this effect, a rack for holding parts with holes that are difficultto electroplate has been described in EP 0 586 770 A1, at least onevibrator being arranged on a mounting rail serving to hold the work andspaced from the places where the mounting rail is resting on a rim of areceptacle. In this event, the circulation of fluid in the holes isgenerated by the oscillations that are transmitted by the vibrator ontothe rack and onto the parts attached to it.

EP 0 446 522 A1 describes a similar facility that is intended to servefor the electroless copper plating of printed circuit boards. Thisfacility is provided with a receptacle for receiving the electrolessprecipitating bath, with a rack for holding the printed circuit boardsimmersed into the precipitating bath and with a vibrator for generatingoscillations from vibration in the printed circuit boards. The vibratoris attached to the supporting rod holding a cage containing the piledprinted circuit boards.

device for removing impurities (bore dust) from bores of printed circuitboards has been disclosed in Patent Abstracts of Japan fromJP-A-1258488, the printed circuit boards being passed in horizontaldirection and in horizontal operational position through a liquid fortreatment, oscillations from vibration in the ultrasonic range beingtransmitted to the liquid for treatment in the neighbourhood of thelevel of transportation of the printed circuit boards so that theprinted circuit boards are exposed to these oscillations as they areguided past the ultrasonic generators.

An arrangement for generating oscillations from vibration in printedcircuit boards guided in horizontal direction and in horizontaloperational position has been described in WO 96/21341 A1 and in DE 4322 378 A1. In this event, the printed circuit boards are brought to movein a combined motion consisting of oscillations from vibration,generated in the printed circuit boards preferably at a frequencysuperior to approximately 1 Hz by means of a counterbalancing vibrator,and of a gliding forward movement. The oscillation movements fromvibration are preferably circular or near-circular, whereby the plane ofthe circle can be arranged in the plane of the boards or normal to it.The movements may also be linear. They preferably follow a sinusoidalcurve. To bring the printed circuit boards to describe such a combinedmovement, thereby transmitting galvanizing current, is extremelycomplicated.

WO 92/01088 A1 discloses a method and a device for moving printedcircuit boards provided with bores during electroplating. In this case,the printed circuit boards are attached to supporting racks and areimmersed into an electroplating liquid in a vertical position. Themethod therein described is preferably used for printed circuit boardswith bores that have an aspect ratio of at least 8:1. For the purpose ofremoving residual matter in the bores, the boards are vibrated at afrequency of at least 4 to 5 Hz, the oscillations generated in theboards running at least partially in direction of the longitudinal axisof the bores and the oscillations from vibration being performed only orat least mainly on the supporting rack of the printed circuit boards.The oscillation generators are accommodated on a conveying and/or on asupporting part for the printed circuit boards. In the document,attention is drawn to the fact that this method and this device alsopermit to remove from the bores gas bubbles that occur during chemicalor electrochemical processes. It also suggests to knock or hit theprinted circuit boards during vibration, thus assisting the gas bubblesin detaching.

DE 90 11 675 U1 describes a device for the surface treatment and theelectroplating of printed circuit boards. For electroplating, theprinted circuit boards are immersed into the liquids for treatment invertical position. For this purpose, the boards are attached to asupporting rack that is slowly moved back and forth in the liquid fortreatment together with the printed circuit boards. The document pointsout that, at a first contact with the liquids for treatment, gas bubblesremain in the bores, these bubbles being particularly difficult toremove from bores having a high aspect ratio. It says that a well-knownmethod for vibrating the boards by striking them by hand with a hammeror a beater is expensive and hardly influences the continuousimprovement of the transfer of material in the barrier layer on the wallof the bore. Moreover, according to this document, success is uncertainwith multilayer circuits having up to 30,000 bores with a diameter of0.3 mm and in which small bubbles may be found. In responding to theseproblems, the document suggests superimposing a comparatively fastrelative movement between the liquid for treatment and the workpieceimmersed into it upon the slow motion of the supporting rack with theprinted circuit boards attached to it. The frequency of the fastrelative movement is said to lie in the infrasound or in the soundrange. To generate the oscillating movement, employment is made of amechanical oscillator or vibrator serving as a mechanical vibratingfacility.

The methods and devices of the art are too complicated or not suited forreliably driving out gas bubbles from very small bores, from pocketholes in particular, even when passage through the plant is horizontal.Furthermore, as yet, no satisfactory solution has been suggested by themethods and devices of the art to carry out the transfer of material inpocket holes.

Therefore, the basic problem of the present invention is to overcome thedrawbacks of the methods and devices of the art and more specifically tofind a device and a method that guarantee the removal of gas bubblesfrom through bores in circuit carriers with a very high aspect ratio, of15:1 and more for example, and from pocket holes having very smalldiameters, such as for example less than 0.2, and relatively high aspectratios, of at least 0.8:1 for example. Additionally, the method shouldbe easy to accomplish and the realization of the device should be madepossible without considerable instrumental expenditure.

The solution of this problem is to provide the device according to claim1, the method according to claim 12, the use of the device according toclaim 23 and the application of the method according to claim 24.Preferred embodiments of the invention are recited in the subclaims.

The device according to the invention serves to process circuit carriersprovided with through holes and/or cavities. The device is suited inparticular for promoting moistening of, for removing gas bubbles fromand/or for increasing the transfer of material in through bores and/orpocket holes in printed circuit boards, through bores having an aspectratio of 15:1 and more and pocket holes having an aspect ratio of 0,8:1and more being particularly suited for secure treatment. The device andthe method of the invention may particularly be utilized in theelectroplating process steps for manufacturing printed circuit boards,such as for example in cleaning, pretreatment and metallization as wellas in further kinds of methods. The invention may be advantageously usedin removing gas bubbles when the bores in circuit carriers are moistenedfor the first time, in removing impurities from the bores duringcleaning and in the transfer of material in the bores to take freshliquid for treatment to the surfaces to be treated (during metallizationfor example).

The device according to the invention is provided with facilitiesserving to contact the liquid for treatment with the circuit carriers,e.g., nozzles such as splash nozzles, injection nozzles and spraynozzles. The device may also be designed is such a way that the circuitcarriers to be treated are passed through a dammed-up bath of the liquidfor treatment. In this case, the facilities for contacting the liquidfor treatment with the circuit carriers include the pipes for feedingthe liquid into the space in which the circuit carriers are guided aswell as damming means such as press rolls and/or walls of receptacles.

Furthermore, the device according to the invention is provided withmeans of transportation and possibly with separate holding means for thecircuit carriers, by means of which the circuit carriers may be conveyedon a horizontal conveying path and in one conveying plane. The means oftransportation may also be designed as holding and guiding means and mayas well serve to supply the current. Clamps or grippers seizing thesides, rotating means such as rolls, wheels and cylinders as well asdragging or pushing devices, in the form of clamps for example, may beutilized as holding, conveying and guiding means.

Pulse generating means are furthermore provided by means of which thecircuit carriers may be excited mechanically in a pulsed manner eitherdirectly, by way of the means of transportation and/or by way of theliquid for treatment. As opposed to sinusoidal oscillations for example,the oscillation forms of pulse excitation cause abrupt changes of motionin the circuit carriers. The excitations meant are striking, hitting orbeating excitations. Repeated excitations are also meant to be pulseexcitations such as oscillations having substantially a rectangular or aserrated shape for example, i.e., such oscillations that have a highproportion of higher-frequency harmonic oscillations if they causeabrupt changes in motion to occur in the circuit carriers in the waymentioned above. The repeating rate of the pulse excitations may lie inthe infrasound or in the sound range. The width chosen for the pulsesshould be such that gas bubbles can be removed in the most efficient waypossible and that the most efficient transfer of material is madepossible in the way according to the invention. Typically, strokes orrectangular pulses respectively are applied with a pulse width of atleast 50 msec.

Accordingly, by pulse generating means we do not mean such means, likee.g. vibrators, that merely generate oscillations in the circuitcarriers. Ultrasound sources that are in contact with the liquid fortreatment are not considered a pulse generating means in accordance withthe invention either since these means also generate sinusoidaloscillations and since the high-frequency oscillations generated bythese sources are not capable of exciting the circuit carriers becauseof their mass, which is too large for this purpose.

As a matter of fact, only the excitation by means of impacts, shocks orbeats proved suited to achieve the inventive effects.

The circuit carriers are conveyed with the help of transportation meanson the horizontal conveying path and in one conveying plane and arethereby brought in contact with the liquid for treatment forspecifically promoting moistening of, for removing gas bubbles fromand/or for increasing the transfer of material in through bores and/orpocket holes in printed circuit boards.

The pulse generating means directly transmit mechanical pulses onto thecircuit carriers by way of the transportation means and/or by way of theliquid for treatment. With relatively simple means the devices accordingto the invention may be readily retrofitted in already existingprocessing plants at low cost. It is often sufficient to have the deviceaccording to the invention accommodated at the entrance of the circuitcarriers in the processing area in order to guarantee moistening of thesurfaces of the circuit carriers with the liquid for treatment.

More specifically, the pulse generating means may be arranged anddesigned in such a way that pulses may be generated whose components actvertically upon the surface of the circuit carriers. In this case,pulses are generated that act substantially vertically upon the surfaceof the circuit carriers. If necessary, the pulses may also be providedwith horizontal pulse components. Pulses with pulse components that actvertically upon the surface of the circuit carrier are particularlyadvantageous since in this case the excitation of the circuit carriersis more effective than in such a case in which pulses are used that actsubstantially parallel to the surface of the circuit carriers as a greatenough traction of the pulse generating means with the surface of thecircuit carriers has to be provided in order for the pulses toefficiently enter the circuit carriers. Additionally, the axes of thebores are generally also normal to the surface of the circuit carriersso that a pulse acting substantially at right angles to the surface maycontribute more efficiently to the transfer of material or to theremoval of gas bubbles than a pulse acting substantially parallel to thesurface. Pulses acting substantially vertically may be readily enteredby means of pulse generating means resting on the surfaces. Verticallyacting pulses may be applied onto the circuit carriers from beneath aswell as from above.

The small through bores and pocket holes may be treated in aparticularly efficient manner when the circuit carriers are conveyed ona substantially horizontal conveying path. In so doing, the circuitcarriers can be led past the nozzles at no great distance from them sothat the liquid for treatment can be delivered to the surfaces of thecircuit carriers and into the bores with a strong flow. Morespecifically, constant flow conditions are achieved for all the surfaceareas thanks to the fact that the distance between the nozzle aperturesand the surfaces may be kept constant. In practical testing, the deviceand the method according to the invention proved to be suitable forprocessing printed circuit films of a very reduced thickness whereasmethods of the art fail in this case.

Rotating transportation means are preferably used. In this event, thepulse generating means may be arranged and designed in such a way thatthe pulses may be generated and/or controlled by a rotation of thetransportation means. Preferred embodiments in which the pulses aregenerated and/or controlled by rotation will be represented hereinafterby way of example.

In a first preferred embodiment of the present invention, thetransportation means employed are at least in parts feed rollers. Thesefeed rollers, or at least some of them, are each provided with asubstantially cylindrical hollow space. On the substantially cylindricalinner wall of the hollow space, at least one projection extends in axialdirection, said projection may be interrupted if so desired. The hollowspace moreover includes at least one body serving as a pulse generatingmeans that rolls along the inner wall of the feed rollers, is carriedalong by the projection, jumps over said projection as it continues torotate, falling down the projection in the process and onto the innerwall of the feed roller. In so doing, pulses are transmitted to the feedrollers and from the feed rollers to the circuit carriers. The hollowspace can be provided with several projections extending in axialdirection each, these projections being regularly or irregularly spacedapart from each other along the periphery of the inner wall. Suchtransportation means will be designated hereinafter as beating rollers.

Projections extending in axial direction may be continuous stumblestrips but also discontinuous strips as well as projections consistingof singular nub-like protuberances and being arranged on an axiallyrunning line. The height of the projections protruding into the hollowspace must be such that the body, which is not attached in the hollowspace, is at least partially taken along by the revolution of the feedroller when the feed roller is rotating, the rotation taking placethrough about 90° for example. The size of the body hereby is directlyrelated to the height of the projections: if a smaller body is used, theprojection may be smaller as well, and vice versa. The size of the bodyand the size of the at least one mating projection must be so large thatthe body, when leaping over the projection and subsequently falling ontothe lower area of the inner wall of the roller, generates a noticeablepulse onto the rollers, said pulse being transmitted to the circuitcarriers.

The body is preferably substantially cylindrical in shape and has thehighest possible weight in order to generate a strongest possible pulsewhen falling onto the inner wall of the rollers, the fall path toohaving to be taken into consideration: if the fall path is long and/orthe weight high, the pulse that is generated is greater than if the fallpath is shorter and/or the weight lower. The body may be a steel rod forexample, said rod being substantially just as long as the hollow space.As a result thereof, a large axial play of the body in the hollow spaceis avoided. The pulse generated is the stronger the larger the diameterof the feed rollers since in this event the fall path of the body islonger.

In an alternative embodiment the hollow space of the feed roller is notcylindrical. The hollow space is rather provided with substantiallyaxially running inner edges. In this case, the section of the hollowspace is preferably square. A body serving as a pulse generating meansand located in the hollow space rolls along the side faces of the hollowspace when the feed roller is made to rotate. Since the body herebyfalls from one inner edge of the hollow space into the other, pulses aretransmitted by the body to the roller and from the roller to the circuitcarriers.

The circuit carriers are preferably conducted through the processingplant in a horizontal conveying plane. The beating rollers may bearranged above or beneath or on both sides of the conveying plane, e.g.,alternately above and beneath the conveying plane. The pulses generatedby the beating roller are repeatedly transmitted to the circuitcarriers, the pulse frequency depending on the rotating velocity of theroller and, as a result thereof, on its diameter and on the rate of feedof the circuit carriers.

Alternatively, pulses may also be transmitted to the circuit carriers bya hammer-like device. A hammer may for example be arranged on the upperside or on the underside of the conveying plane in such a manner that itbeats the surface of the circuit carriers as they pass by. The hammermay be driven or controlled respectively by the rotation of thetransportation means.

In another embodiment according to the invention the transportationmeans are at least partially connected to at least one wheel each, eachwheel being provided on its periphery with at least one projection, theyare rotatably carried together with the at least one wheel with onecommon axis and the beater, which is springy or spring mounted andserves as a pulse generating means, is resting on the periphery of theat least one wheel in such a manner that mechanical pulses aretransmitted to the at least one wheel and, as a result thereof, to thetransportation means preferably rigidly connected to the at least onewheel and from said transportation means to the circuit carriers by thebeater when gliding over the projection.

One or several wheels may for example be attached together with a feedroller or with rolls or wheels to a common axis so that the wheel or thewheels are caused to rotate in synchronism with the rotation of the feedroller, the rolls or the wheels.

The wheel may be provided on its periphery with one or severalprojections that are held apart from each other for example. In caseseveral projections are provided for, said projections may be positionedat regular or irregular intervals around the periphery of the wheel. Ina particularly preferred embodiment the wheels are designed likeratchets, i.e., the wheel has a serrated circumference.

The beater that rests on the periphery of the wheel or wheels may bedesigned as a lever which is biassed by a spring and is pressed againstthe periphery. In another embodiment the beater may also be designed asa pin that is resiliently pressed against the periphery in asubstantially tangential or even radial direction by means of amechanical spring or of pneumatic means for example.

The rotation of the feed rollers, the wheels or the rolls causes thewheels provided with the projections to rotate as well so that thebeater glides over at least one projection, is strongly accelerated andis struck against the periphery of the wheel by the force of the springso that mechanical pulses are transmitted to the wheel and the feedroller, the wheels or the rolls connected to the wheel and from there inturn to the circuit carriers. The force of the spring and the mass ofthe beater must be such that the mechanical pulses generated by thebeater striking the periphery of the wheel be strong enough.

The pulse generating means of this embodiment may be used with ahorizontally and with a vertically oriented conveying plane alike andmay be arranged above as well as beneath the conveying plane when thecircuit carriers are guided in a horizontal conveying plane. The pulsesexerted onto the circuit carriers are more specifically repeat pulses.The pulse frequency is conditional on the rotating velocity of thetransportation means and thus depends on the diameter of thetransportation means and on the rate of feed of the circuit carriers aswell.

In another embodiment according to the invention the transportationmeans are at least partially equipped with one magnetic core each. Thetransportation means of interest are preferably feed rollers. At leastone electromagnet serving as a pulse generating means is assigned toeach transportation means fitted with the magnetic core in such a mannerthat, by having current supplied into the electromagnet in a pulsed way,a force may be exerted onto the transportation means fitted with themagnetic core in such a way that mechanical impulses resembling strokesare generated in the circuit carriers by way of the transportationmeans.

The magnetic core may be made of a ferromagnetic material such as steelfor example so that, when current is supplied to the electromagnet, anattractive force acts between the electromagnet and the ferromagneticcore and that the transportation means is lifted from the circuitcarriers.

The transportation means may also be equipped with a magnetized material(permanent magnet). The permanent magnet is rotated by the rotation ofthe transportation means. If the permanent magnet is arranged in thetransportation means in such a manner that the poles of the magnet areoriented in radial direction, it is at times the one pole and at timesthe other pole of the magnet that points toward the electromagnet. Ifthe direction of the magnetic field of the electromagnet is not modifiedin time, the effect exerted upon the transportation means may berepulsive or attractive depending on the rotational position of thepermanent magnet. By synchronization of a train of pulses of themagnetic field of the electromagnet, the transportation means may beeither attracted in a pulsed manner by the electromagnet or repulsed byit. An alternately attractive and repulsive effect may also be achievedby supplying the electromagnet with pulsed current in an adequatemanner. This embodiment is very advantageous since mechanical pulses arethus exerted onto the circuit carriers in alternating directions so thatgas bubbles located in the small bores may more readily be detached.Since on the other hand, pulsating current is always supplied to theelectromagnet when a repulsive effect is exerted onto the transportationmeans for example, mechanical shock pulses exclusively may betransmitted to the transportation means and thus to the circuitcarriers.

An additional force that is oriented toward the circuit carriers, theforce of gravity and/or the force of a spring and/or a magnetic forcefor example, may also preferably act on the transportation means. Inthis event it is possible, in using a ferromagnetic core or bysynchronizing the current pulses with the rotation of the transportationmeans when a permanent magnet is employed, to exert onto thetransportation means a force that acts against this additional force sothat the transportation means are lifted from the circuit carriers. Whenthe electromagnet is switched off, the transportation means is movedback again by this additional force to the circuit carriers so that,when the transportation means strike the surfaces of the circuitcarrier, mechanical pulses are thus transmitted to the circuit carriers.This is of course only possible with the proviso that the additionalforce is smaller than the force exerted by the electromagnet. If theadditional force used is merely the force of gravitation, thetransportation means, a feed roller for example, may be positioned abovea horizontally oriented transportation plane. In case repeat pulses areintended to be exerted onto the circuit carriers, the pulse frequency isconditional on the time needed by the transportation means to fall backonto the circuit carriers after having been lifted from theelectromagnet.

If a permanent magnet is employed in the transportation means the pulsegenerating means in this further embodiment may be used in ahorizontally and in a vertically oriented conveying plane alike and, incase the circuit carriers are guided in a horizontal conveying plane,they may be positioned above as well as underneath the conveying plane.The pulses may be used repeatedly, the pulse frequency depending on theembodiment: if the selected variant is such that the repetition rate iscontrolled by the rotation of the transportation means, the pulsefrequency depends on the diameter and on the rate of feed of the circuitcarriers and, as a result thereof, on the rotary frequency of thetransportation means. Otherwise, a discretional pulse frequency may beused, an upper limit being given by the inertia of masses of the overallsystem, though.

In still another embodiment according to the invention, pulse generatingmeans are positioned within the liquid for treatment on the conveyingplane by means of which pulses are transmitted via the liquid fortreatment to the circuit carriers conveyed in the plane oftransportation. In the pulse generating means, the pulses are preferablygenerated in an electromechanical way and/or are driven by compressedair and are transmitted to the liquid for treatment and from the liquidfor treatment to the circuit carriers via at least one transmissionmeans, a membrane or an oscillator for example. Pulse generating meansproducing infrasound or sound waves are utilized for the purpose forexample, the shape of the pulse being as indicated herein above. Thetransmission means by means of which the pulsed waves are transmitted tothe liquid for treatment is positioned as near as possible to theconveying plane for the circuit carriers in order to effect aparticularly efficient transmission of the mechanical pulses to thecircuit carriers. The pulse generating means are preferably arranged insuch a way that the transmission means are oriented parallel to theconveying plane.

The pulse generating means of this embodiment also permit to generatetrains of pulses. The pulse frequency may be adjusted freely inconformity with the inertia of masses of the system. A frequency ispreferably adjusted in the infrasound range. As explained herein above,sources of ultrasound are not suited for the pulsed excitation of thecircuit carriers.

Still another possibility consists in generating pulses in nozzles thatabruptly deliver the liquid for treatment toward the surfaces of thecircuit carriers. In this case, the liquid is delivered to the circuitcarriers in pulses, thus exerting pulses onto their surfaces.

A so-called fan nozzle out of which the liquid is delivered throughextremely fine nozzle apertures against the surfaces of the circuitcarriers is connected to an intermittent beater operated with compressedair so that the pulses are entered into the nozzle body. Other methodsfor generating pulses may also be used. The complete flow of liquid orpart of it may for example be constantly interrupted in an abrupt mannerso that a high pressure builds up in the fluid during the interruptionin the area in which the liquid is fed, said pressure dropping abruptlyas the supply of liquid is being resumed, so that the liquid exits thenozzles by jerks. The pulses in the nozzle body are transmitted to theliquid for treatment exiting the nozzle so that a pulsating jet ofliquid is produced which is delivered to the surfaces. The transmissionof pulses onto the nozzle body additionally thwart the obstruction ofthe extremely fine nozzle apertures.

The present invention resides in any one of the embodiments indicatedand described herein above. However, it is also possible to usecombinations of the various embodiments for the purpose of operatingside by side several pulse generating means in one processing plant onthe one side and of realizing combinatory solutions for the generationof pulses on the other side. Pulses may for example also be transferredindirectly through the liquid for treatment onto the work by means ofratchet-like pulse generating means. Another possibility is toadditionally amplify pulses generated by electromagnets in having therollers on which the electromagnetic force acts configured as beatingrollers accommodating in their hollow space metal rods adapted togenerate pulses.

Reference is now made to the following drawings in order to explain moreexplicitly the device and the method of the invention.

FIG. 1 schematically illustrates a continuous processing plant;

FIG. 2 shows a cross section through a beating roller with a stumblestrip;

FIG. 3 shows a cross section through a beating roller with four stumblestrips;

FIG. 4 shows cross sections through a beating roller in various stagesof rotation;

FIG. 5 shows a cross section through a beating roller with a squareinner cross section;

FIG. 6 shows a top view of a pulse generating means designed as aratchet;

FIG. 7A shows a view of a pulse generating means designed as a ratchetseen from the front;

FIG. 7B shows a view of a pulse generating means designed as a ratchetseen from the front;

FIG. 7C shows a detail of the pulse generating means designed as aratchet;

FIG. 7D shows a view of a pulse generating means designed as a ratchetseen from the front;

FIG. 8 shows a side view of a pulse generating means with anelectromagnet;

FIG. 9 shows a side view of a pneumatic intermittent beater in theprocessing plant;

FIG. 10 shows a side view of a partial view of a plant with twopneumatic intermittent beaters;

FIG. 11 shows a front view of a pneumatic intermittent beater;

FIG. 12 shows a side view of fan nozzles that are fitted with pneumaticintermittent beaters;

FIG. 13 like FIG. 12 but with a pulse generating means configured as aratchet.

FIG. 1 shows a side view of a processing plant with a processing chamber1 in which printed circuit boards PCB are conducted in a horizontalconveying plane 2 in the direction of transportation 3. The chamber 1 isformed by an entrance wall 4 and by an exit wall 5, by side walls 6, achamber floor 7 and a chamber lid 8. Liquid for treatment is containedin a reservoir (not here presented), preferably underneath theprocessing chamber 1. The liquid for treatment is delivered to thenozzles 10 by way of pipelines 9. The nozzles 10 are designed as splashnozzles. For this purpose they are for example provided with a jetchamber having a slot oriented toward the conveying plane 2. The liquidfor treatment exiting the nozzles 10 is delivered into the bores in theprinted circuit boards PCB and is passed through said bores ifnecessary. The liquid is again drained through openings that have notbeen illustrated herein toward the liquid reservoir after it was broughtto contact the printed circuit boards PCB.

The printed circuit boards PCB are conveyed in the direction oftransportation 3 into the chamber 1 through the entrance slot 11 in theentrance wall 4. They are passed through the chamber 1 and are advancedout of the chamber 1 through the exit slot 12 in the exit wall 5.

Inside the chamber 1 there are provided feed rollers 13 and 14, the feedrollers 13 being positioned underneath and the feed rollers 14 above theconveying plane 2. The feed rollers 13, 14 serve to guide and convey theprinted circuit boards PCB in the chamber 1. On their outer side, theyare made at least in parts of an elastic material in order to preventthe surfaces of the printed circuit boards PCB from being damaged and toachieve the greatest possible traction between the rollers 13, 14 andthe printed circuit boards PCB.

The feed rollers 13 and 14 arranged above and underneath the plane oftransportation 2 may be provided with pulse generating means 21, 31according to the invention (FIGS. 2 through 7). Furthermore, pulsegenerating means 40 may be provided (FIG. 8). In a particular embodimentpulse generating means 50 may also be arranged above and/or underneaththe plane of transportation 2 between the feed rollers 14 (FIG. 9through 12). If necessary liquid for treatment must therefore also beprovided above the conveying plane 2 in order to allow the mechanicalpulses generated in the pulse generating means 50 to be entered into theprinted circuit boards PCB via the liquid. For this purpose, thedischarge of the liquid for treatment out of the chamber 1 and into theliquid reservoir is regulated in such a manner that the chamber 1 isfilled up to a level 60 above the conveying plane 2. The rollers 13′ and14′ arranged at the entrance slot 11 and the rollers 13″ and 14″positioned at the exit slot 12 also serve as squeeze rolls whosefunction it is to retain the liquid for treatment and to prevent or atleast hinder its exit from chamber 1.

FIG. 2 shows the cross section of an embodiment of a feed roller 14 witha hollow space 20 and with a metal rod 21 contained in said hollow space20, said feed roller serving as a pulse generating means. A stumblestrip 22 is accommodated on the inner wall of the hollow space 20. Themetal rod 21 is not fastened in the hollow space 20. The length of themetal rod 21 is slightly shorter than the axial length of the hollowspace 20. It is thus made certain that the metal rod 21 only has littleplay in axial direction.

FIG. 3 shows the cross section of another variant of a feed roller 14with a hollow space 20 and with a metal rod 21 contained in said hollowspace 20. In this case, four stumble strips 22 are accommodated in sucha manner that they are offset at an angle of 90° relative to each other.In this case, the metal rod 21 is not fastened in the hollow space 20either.

FIG. 4 shows the way of operation of the feed roller 13, 14 providedwith the hollow space 20 and with a stumble strip 22 in various stagesof rotation. In this case the feed roller 14, which otherwise is notmade of metal, is fitted on its inner side with a metal cylinder 23 thatprovides the feed roller 14 with the required stability. The roller 14rotates in the direction of rotation 24 shown.

In part A of FIG. 4 the roller 14 is shown with the stumble strip 22being at its lowest point. In this position, the strip 22 has alreadyslightly lifted the rod 21 from its lowermost position. As rotationcontinues, the strip 22 has been further rotated about 30°, according topart B of FIG. 4, and has taken the rod 21 along by just this section.In part C of FIG. 4 the roller 14 has been further rotated 30°. Thestrip 22, which has taken the rod 21 along, has also been furtherrotated 30°. As the roller 14 is rotated further, the rod 21 springsover the strip 22 and falls onto the lowest point of the inner wall. Amechanical pulse is thus transmitted to the roller 14 and to a printedcircuit board PCB contacting the roller 14 (FIG. 1). As the roller 14 isrotated further, the rod 21 first rolls down along the inner wall of thehollow space 20 and is only taken along by the strip 22 again as soon assaid strip is capable of taking the rod 21 along.

FIG. 5 shows another variant of a beating roller 14. In this case, thehollow space 20 in the roller 14 is square in section. For the purpose,a rectangular tube 23 with a square section is embedded within theroller 14. In this case, a metal rod 21 falls from one corner (inneredge) 25 to the other as the roller 14 is rotating so that, in so doing,pulses are exerted onto the roller 14 and from there onto the printedcircuit boards PCB.

FIG. 6 shows a top view of a feed roller 13, 14 with one ratchet 30attached to either front sides. The ratchets 30 lie on the same axis asthe roller 13, 14 and are rigidly connected to it.

Beaters 31 are abutting the periphery of each of the ratchets 30 underthe force of a spring, said beaters being accommodated in bearings insuch a way that they may be deviated.

This arrangement is shown in detail from the front in FIG. 7A. In thiscase, the roller 13, 14 is hidden by the ratchet 30. The ratchet 30consists of a body 38 and of teeth 36 arranged on the body 38. A beater31 designed as a lever is accommodated on the bearing 32 in such a waythat it may be deviated. The bearing 32 is provided for on a part 34that is attached to a mounting part 35 in the chamber 1. The beater 31is pressed against the periphery of the ratchet 30 by means of a spring33.

The ratchet 30 is rotated by the roller 13, 14 in the direction 24. Thiscauses the beater 31 to be deviated by the teeth 36 against the force ofthe spring. When skipping a tooth 36, the beater 31 springs into thespace 37 between the teeth 36, thus exerting a pulse onto the ratchet 30and, as a result thereof, onto the roller 13, 14. The pulse that hasbeen transmitted to the roller 13, 14 is transmitted to the printedcircuit boards PCB.

FIG. 7B shows an alternative variant of the beater 31. This beater 31differs in shape from the one shown in FIG. 7A.

Another variant of the beater 31 is illustrated in FIG. 7C. As comparedto the one represented in FIG. 7A, this beater 31 is characterized by amodified way of transmitting the force of the spring.

A further variant of the beater 31 is represented in FIG. 7D. Thisbeater 31 is not provided with a lever but is designed as a striking pinwhich is biassed by a spring 33. The spring is carried on bearings inthe mounting part 35 of the chamber 1.

The roller 13, 14, which takes the ratchet 30 along, rotates the ratchet30 with the body 38, the teeth 36 as well as with the spaces 37 betweenthe teeth 36 in the direction 24. The striking pin 31 is deviated by theteeth 36 against the force of the spring 33 and strikes, upon glidingover the teeth 36, into each space 37, pulses being transmitted in theprocess onto the ratchet 30 and thus onto the roller 13, 14 from wherethey are finally transmitted to the printed circuit board PCB.

FIG. 8 illustrates a further embodiment of the invention. The upperroller 14 is designed with a ferromagnetic core, here in the form of abar magnet 23 in the hollow roller 14. Inside the hollow space 20 thereis provided an axis 26 about which the roller 14 is running. A stop 43is moreover accommodated above the axis 26 outside the body of theroller 14. If the pole piece 45 is suitably designed, the stop 43 may berelinquished. An elastic rest 42 is provided for underneath the axis 27of the lower roller 13 to serve as a bearing insert in order to reducethe wear of the bearings and to achieve a greater shock amplitude ontransmitting the pulses.

In close proximity to the upper roller 14 there is further arranged anelectromagnet 40 configured as a pulse generating means that is providedwith a coil 41 and electric feed lines 44. By supplying the coil 41 ofthe electromagnet 40 with a pulsed current, a magnetic field isgenerated at the pole piece 45 of the electromagnet 40 so that the barmagnet 23 in the upper roller 14 is attracted by the electromagnet 40.This causes the roller 14 to be lifted. When a pulse is over, the upperroller 14 falls back in its initial position and thus exerts a pulsedirectly onto the printed circuit boards PCB (not shown) conveyedbetween the rollers 13 and 14.

FIG. 9 represents another embodiment of the invention. The printedcircuit boards PCB are conveyed within the chamber 1 between the rollers13 and 14. The chamber 1 is completely filled with the liquid fortreatment essentially by means of adequate measures. A pneumaticintermittent beater 50 is accommodated between the upper rollers 14 inclose proximity to the conveying plane 2 in which the printed circuitboards PCB are guided. With the help of the pneumatic intermittentbeater 50, mechanical pulses 57 are transmitted via the front face ofthe beater 56 through the liquid for treatment to the printed circuitboards PCB. If the arrangement is adequate, the pulses may also betransmitted from the pneumatic intermittent beater 50 to the printedcircuit boards PCB via the rollers 13, 14.

FIG. 10 shows an array of two pneumatic intermittent beaters 50 in onechamber 1. The pneumatic intermittent beaters 50 are accommodated aboveor underneath the conveying plane 2 for the printed circuit boards PCBbetween the rollers 13 or the rollers 14 respectively. Pulsedoscillations 57 are generated in the pneumatic intermittent beaters 50and are transmitted to the printed circuit boards PCB by way ofoscillators 56. In order to reinforce the effect of the pulses in theconveying plane 2, reflecting means 58, such as sheet metal for example,are arranged on that side of the conveying plane 2 that is averse to thepneumatic intermittent beaters 50.

FIG. 11 represents a possible embodiment of a pneumatic intermittentbeater 50 that is mounted between two upper rollers 14 that are notillustrated in the figure. FIG. 11 is a section through a plant normalto the direction of transportation. The printed circuit boards PCB areguided in the conveying plane 2. The pneumatic intermittent beater 50consists of a piston with a controllable valve 51, of a feed pipe forthe compressed air 52 and of a drain pipe for the compressed air 53. Thepiston with the controllable valve 51 is rigidly connected to anoscillator 56 serving as a transmission means. The pneumaticintermittent beater 50 is arranged in close proximity to the conveyingplane 2 and is hung on a device 54 by means of springs 55.

The level 60 of the liquid for treatment is situated above the conveyingplane 2 and the oscillator 56 so that the printed circuit boards PCB andthe oscillator 56 of the pneumatic intermittent beater 50 are completelyimmersed into the liquid for treatment.

The compressed air, which is admitted by a valve into the piston, causesthe preferably heavy piston to accelerate downward in the direction ofthe arrow 57 and generates mechanical pulses 57 in the oscillator 56 onimpinging on said oscillator 56, said pulses being transmitted to theprinted circuit boards PCB in the conveying plane 2 through the liquidfor treatment.

FIG. 12 represents a further embodiment of the invention: printedcircuit boards PCB that are conducted in the conveying plane 2 throughthe processing chamber 1 pass through fan nozzles 70 between the feedrollers 13 and 14, said nozzles being provided with jet chambers 71 withnozzle apertures 72. Pneumatic intermittent beaters 50 communicate withthe jet chambers 71 via oscillators 56 that transmit pulses 57 to thenozzles 70 so that the liquid for treatment that is delivered by thenozzles 70 to the surfaces of the printed circuit boards PCB impinges onthem in pulsated jets. The nozzles 70 are arranged in such a manner thatthe nozzle apertures 72 are located underneath the level 60 of theliquid in the chamber 1. For the rest, the device corresponds to the oneillustrated in FIG. 11 so that reference is made to that description.FIG. 13 shows another embodiment of the invention, this embodimentconstituting an improvement of the arrangement represented in FIG. 12.Furthermore, in this embodiment, the principle already shown in theFIGS. 7 and 7A-7D for generating pulses is realized. The reader isreferred to the description of the FIGS. 7 and 7A-7D with regard to theelements of the device and to the corresponding reference numeralscarried forward from said Figs.

In this case, the printed circuit boards PCB are conveyed past apreferably solid metal plate 73 positioned at a distance of only a fewmillimeters (e.g., 1-3 mm) from the conveying plane 2 and through whichthe pulses are transferred by way of the liquid for treatment to theprinted circuit boards PCB. For this purpose, the metal plate 73 isarranged within the liquid for treatment together with an anvil 75. Themetal plate 73 is preferably soldered to the anvil 75. The anvil 75should at least in parts protrude from the liquid for treatment. The twoelements are normally resting and are connected to the processingfacility in a manner that has not been illustrated herein. The metalplate 73 extends over the entire width of the conveying path so thatpulses may be transmitted onto the printed circuit boards PCB on theentire width of the conveying path.

Pulses are generated by a ratchet-like pulse generating means 30 thatmay be configured in the same manner as the pulse generating means inthe FIGS. 7 and 7A-7D and that functions in the same way. By way of thelever 31 and the hammer 74 connected to said lever 31, impacts aretransferred onto the anvil 75 and the metal plate 73 so that pulses maybe generated in the printed circuit boards PCB.

LISTING OF REFERENCE NUMBERALS

-   1 processing chamber-   2 conveying plane-   3 direction of transportation-   4 entrance wall at the chamber 1-   5 exit wall at the chamber 1-   6 side walls of the chamber 1-   7 floor of the chamber 1-   8 lid of the chamber 1-   9 feed pipe to the nozzles 10-   10 nozzles-   11 entrance slot-   12 exit slot-   13 lower transportation mean/feed rollers-   13′ lower transportation means/feed roller at the entrance slot 11-   13″ lower transportation means/feed roller at the exit slot 12-   14 upper transportation means/feed rollers-   14′ upper transportation means/feed roller at the entrance slot 11-   14″ upper transportation means/feed roller at the exit slot 12-   20 hollow space in the rollers 13, 14-   21 pulse generating means, body, metal rod-   22 projection, stumble strip-   23 inner lining, ferromagnetic core, steel cylinder, rectangular    tube in the rollers 13, 14, bar magnet-   24 direction of rotation of the rollers 13, 14-   25 inner edge in the rectangular tube 23-   26 axis of the upper roller 14-   27 axis of the lower roller 13-   30 wheel provided with projections 36, ratchet-   31 pulse generating means, beater, striking pin-   32 bearing for the beater 31-   33 spring at the beater 31-   34 fastening part for the beater 31-   35 mounting part for fastening the beater 31-   36 projection, teeth at the beater 31-   37 space between the teeth 36-   38 body of the wheel, the ratchet 30-   40 pulse generating means, electromagnet-   41 coil of the electromagnet 40-   42 elastic rest for accommodating the lower roller 13-   43 stop for the upper roller 14-   44 electric feed lines for the electromagnet 40-   55 pole piece of the electromagnet 40-   50 pulse generating means, pneumatic intermittent beater-   51 piston with controllable valve-   52 feed line for delivering compressed air to the pneumatic    intermittent beater 50-   53 drain pipe for carrying the compressed air away from the    pneumatic intermittent beater 50-   54 suspension device for the pneumatic intermittent beater 50-   55 springs on the suspension device 54-   56 pulse generating means, oscillator at the pneumatic intermittent    beater 50-   57 pulses-   58 reflecting means-   60 level of the liquid for treatment-   70 fan nozzles-   71 jet chambers of the fan nozzles 70-   72 nozzle apertures in the fan nozzles 70-   73 metal plate-   74 hammer-   75 anvil

1. A device for treating circuit carriers (PCB) provided with through holes and/or cavities with facilities for contacting the liquid for treatment with the circuit carriers (PCB) as well as transportation means (13, 14) for the circuit carriers (PCB), comprising means for conveying the circuit carriers (PCB) in a horizontal conveying path and in one conveying plane (2), wherein pulse generating means (21, 31, 40, 50) are provided for comprising means for directly exciting circuit carriers (PCB) via any of (a) the transportation means (13, 14) and (b) the liquid; for treatment by mechanical pulses, characterized in that the transportation means (13, 14) are at least partially equipped with one magnetic core (23) each and that at least one electromagnet (40) comprises a pulse generating means to each of the transportation means (13, 14) equipped with the magnetic core (23) whereby current supplied in a pulsed manner to the at least one electromagnet (40), causes a force to be exerted onto the transportation means (13, 14) equipped with the magnetic core in such a way that mechanical pulses are generated in the circuit carriers (PCB) through the transportation means (13, 14).
 2. The device according to claim 1, characterized in that an additional force that is oriented toward the circuit carriers (PCB) acts on the transportation means (13, 14) and comprises means for the transportation means (13, 14) to be lifted off the circuit carriers (PCB) by the force exerted by the at least one electromagnet (40) and moved back toward the circuit carriers (PCB) upon switching off the at least one electromagnet (40) by way of the additional force for mechanical pulses to be transmitted to the circuit carriers (PCB).
 3. The device according to claim 2, characterized in that the force that acts on the transportation means (13, 14) and is oriented toward the circuit carriers (PCB) is any of (a) the force of gravitation; (b) the force of a spring; and (c) a magnetic force.
 4. A device for treating circuit carriers (PCB) provided with through holes and/or cavities with facilities for contacting the liquid for treatment with the circuit carriers (PCB) as well as transportation means (13, 14) for the circuit carriers (PCB), comprising means for conveying the circuit carriers (PCB) in a horizontal conveying path and in one conveying plane (2), wherein pulse generating means (21, 31, 40, 50) are provided for comprising means for directly exciting circuit carriers (PCB) via any of (a) the transportation means (13, 14) and (b) the liquid; for treatment by mechanical pulses, characterized in that the transportation means (13, 14) are at least partially linked to at least one wheel (30) each, said at least one wheel being provided on its periphery with at least one projection (36), and rotatably carried on bearings together with the at least one wheel (30) on one common axis and that one springy or resiliently accommodated beater (31) comprises a pulse generating means abutting the periphery of the at least one wheel (30) in such a manner whereby the beater (31) gliding over the projection (36) to the at least one wheel (30) produces mechanical pulses which are transmitted to the transportation means (13, 14) connected to the at least one wheel (30) and from said transportation means (13, 14) to the circuit carriers (PCB).
 5. A device for treating circuit carriers (PCB) provided with through holes and/or cavities with facilities for contacting the liquid for treatment with the circuit carriers (PCB) as well as transportation means (13, 14) for the circuit carriers (PCB), comprising means for conveying the circuit carriers (PCB) in a horizontal conveying path and in one conveying plane (2), wherein pulse 2 generating means (21, 31, 40, 50) are provided for comprising means for directly exciting circuit carriers (PCB) via any of (a) the transportation means (13, 14) and (b) the liquid; for treatment by mechanical pulses, characterized in that the transportation means (13, 14) are configured so as to be rotatable and that the pulse generating means (21, 31, 40, 50) are arranged and designed to comprise means whereby the pulses caused by rotation of the transportation means (13, 14).
 6. The device according to any one of claims 5, 4 and 1, characterized in that the pulse generating means (21, 31, 40, 50) comprise means whereby pulses generated have pulse components acting vertically on the surface of the circuit carrier.
 7. A method for treating circuit carriers provided with through holes and/or cavities in which (a) the circuit carriers (PCB) are conveyed on a horizontal conveying path and in one conveying plane (2) with the help of transportation means (13, 14) and (b) with the circuit carriers being brought into contact with a liquid for treatment in the process, and (c) wherein mechanical pulses are transmitted directly to the circuit carriers (PCB) via any of (i) the transportation means (13, 14) and (ii) the liquid for treatment by means of pulse generating means (21, 31, 40, 50), characterized in that (d) pulse generating means (50) are arranged within the liquid for treatment on the conveying plane (2), (e) pulses are transmitted by the pulse generating means (50) to the circuit carriers (PCB) that are conveyed in the conveying plane (2) through the liquid for treatment, (f) wherein the pulses are generated in the pulse generating means (50) in an electromechanical and/or in a compressed air driven manner and are transmitted by way of at least one transmission means (56) to the liquid for treatment and from said liquid for treatment to the circuit carriers (PCB).
 8. A method for treating circuit carriers provided with through holes and/or cavities in which (a) the circuit carriers (PCB) are conveyed on a horizontal conveying path and in one conveying plane (2) with the help of transportation means (13, 14) and (b) with the circuit carriers being brought into contact with a liquid for treatment in the process, and (c) wherein mechanical pulses are transmitted directly to the circuit carriers (PCB) via any of (i) the transportation means (13, 14) and (ii) the liquid for treatment by means of pulse generating means (21, 31, 40, 50), characterized in that (d) the transportation means (13, 14) are at least partially equipped with one magnetic core (23) each and (e) that at least one electromagnet (40) is assigned as a pulse generating means to each of the transportation means (13, 14) equipped with the magnetic core (23) in such a manner that, by supplying current in a pulsed manner to the at least one electromagnet (40), a force is exerted onto the transportation means (13, 14) equipped with the magnetic core in such a way that mechanical pulses are generated in the circuit carriers (PCB) through the transportation means (13, 14).
 9. The method according to claim 8, characterized in that (f) an additional force that is oriented toward the circuit carriers (PCB) acts on the transportation means, so that the transportation means (13, 14) are lifted off the circuit carriers (PCB) by the force that is exerted by the at least one electromagnet (40) and is moved back toward the circuit carriers (PCB) upon switching off the at least one electromagnet (40) by way of the additional force and that mechanical pulses are thus transmitted to the circuit carriers (PCB).
 10. The method according to claim 9, characterized in that the force of any of (i) gravitation; (ii) the force of a spring; and (iii) a magnetic force acts on the circuit carriers (PCB).
 11. A method for treating circuit carriers provided with through holes and/or cavities in which (a) the circuit carriers (PCB) are conveyed on a horizontal conveying path and in one conveying plane (2) with the hem of transportation means (13, 14) and (b) with the circuit carriers being brought into contact with a liquid for treatment in the process, and (c) wherein mechanical pulses are transmitted directly to the circuit carriers (PCB) via any of (i) the transportation means (13, 14) and (ii) the liquid for treatment by means of pulse generating means (21, 31, 40, 50), characterized in that (d) the transportation means (13, 14) are at least partially linked to at least one wheel (30) each and rotatably carried on bearings together with the wheel (30) on one common axis, (e) the at least one wheel (30) being provided on its periphery with at least one projection (36), (f) that one springy or resiliently accommodated beater (31) serving as a pulse generating means is abutting the periphery of the at least one wheel (30) and glides over the at least one projection (36) on rotation of the at least one wheel (30) and (g) wherein mechanical pulses are transmitted by the beater (31) gliding over the projection (36) to the at least one wheel (30) and, as a result thereof, to the transportation means (13, 14) connected to the at least one wheel (30) and from said transportation means (13, 14) to the circuit carriers (PCB).
 12. A method for treating circuit carriers provided with through holes and/or cavities in which (a) the circuit carriers (PCB) are conveyed on a horizontal conveying path and in one conveying plane (2) with the help of transportation means (13, 14) and (b) with the circuit carriers being brought into contact with a liquid for treatment in the process, and (c) wherein mechanical pulses are transmitted directly to the circuit carriers (PCB) via any of (i) the transportation means (13, 14) and (ii) the liquid for treatment by means of pulse means (21, 31, 40, 50), characterized in that (d) the transportation means utilized are at least partially feed rollers (14) that are each provided with one substantially cylindrical hollow space (20) having a substantially cylindrical inner wall, (e) at least one body (21) serving as a pulse generating means rolls down along the inner wall in the hollow space (20) when the feed rollers (14) are rotating, (f) thereby springing over a projection (22) extending in axial direction on the inner wall, and (g) so that pulses are transmitted to the feed rollers (14) and from the feed rollers (14) to the circuit carriers (PCB) as the at least one body (21) falls down and impinges on the inner wall of the feed roller.
 13. The method according to claim 12, characterized in that the body (21) is substantially cylindrical in shape.
 14. A method for treating circuit carriers provided with through holes and/or cavities in which (a) the circuit carriers (PCB) are conveyed on a horizontal conveying path and in one conveying plane (2) with the help of transportation means (13, 14) and (b) with the circuit carriers being brought into contact with a liquid for treatment in the process, and (c) wherein mechanical pulses are transmitted directly to the circuit carriers (PCB) via any of (i) the transportation means (13, 14) and (ii) the liquid for treatment by means of pulse generating means (21, 31, 40, 50), characterized in that rotating transportation means (13, 14) are employed and that the pulses are caused by the rotation of said transportation means (13, 14).
 15. The method according to any one of claims 14, 12, 11, 8 and 7, characterized in that such pulses are generated by means of the pulse generating means (21, 31, 30, 50) that have pulse components acting vertically on the surface of the circuit carriers.
 16. A device for treating circuit carriers (PCB) provided with trough holes and/or cavities with facilities for contacting the liquid for treatment with the circuit carriers (PCB) as well as transportation means (13, 14) for the circuit carriers (PCB), comprising means for conveying the circuit carriers (PCB) in a horizontal conveying path and in one conveying plane (2), wherein pulse generating means (21, 31, 40, 50) are provided for comprising means for directly exciting circuit carriers (PCB) via any of (a) the transportation means (13, 14) and (b) the liquid; for treatment by mechanical pulses, characterized in that pulse generating means (50) are provided for within the liquid for treatment on the conveying plane (2), for transmitting pulses to the circuit carriers (PCB) that are conveyed in the conveying plane (2) through the liquid for treatment, with the pulse generating means (50) comprising means for generating pulses in any of (a) an electromechanical manner, and (b) compressed air driven manner for transmitting pulses by way of at least one transmission means (56) to the liquid for treatment and from said liquid for treatment to the circuit carriers (PCB). 